Screens and surfaces of cell phones, tablets, and other hand-held electronic devices are susceptible to fingerprints and smudge deposition. The windows of high-rise buildings can develop stains due to dust deposition from rain or ice droplets. Automobile bodies and windshields become dirty from mud and dust. Such deposits affect the aesthetic appeal of objects and decrease our enjoyment. When these deposits accumulate on the screens of hand-held electronic devices or windows and windshields, they deteriorate display quality and diminish one's ability to use the device or to operate the vehicle. All these issues can be alleviated with anti-smudge coatings that are also optically clear and durable.
Currently, there are no durable amphiphobic (oil- and water-repellent) and optically-clear coatings on the market for hand-held electronic devices, windshields, or the windows of high-rises. Perfluoropolyether-silane-based liquids are sold as coatings for hand-held electronic devices. These coatings are of limited use because they are not wear resistant.
A typical polyurethane or epoxy coating is fairly water repellent, but does not have oil repellent properties. Accordingly, neither polyurethane nor epoxy is an amphiphobic coating. Polyurethanes are produced by reacting an isocyanate containing two or more isocyanate groups per molecule (R—(N═C═O)n with n ≥2) with a polyol containing on average two or more hydroxy groups per molecule (R′—(OH)n with n ≥2), optionally in the presence of a catalyst, see Scheme 1. The properties of polyurethane are greatly influenced by the types of isocyanates and polyols from which it was made. Epoxy coatings are produced by reacting a resin with a hardener (also called an activator), see FIG. 10.

Two-component polyurethane coatings have two mutually reactive components that are stored separately. One component bears hydroxyl groups. The other component bears isocyanate groups. The two different components are typically stored in pre-polymer or oligomeric form to reduce vapour pressures for safety and toxicity reasons. A pre-polymer is a medium molecular weight species, between a molecule and a polymer. Pre-polymers have a lower vapour pressure than its corresponding low molecular weight molecular reactive components (Gite, V. et al. Prog. Org. Coat. 2010, 68, 307). When the two different components are mixed together, the hydroxyl groups react with the isocyanate groups to produce a crosslinked PU film or coating, as shown below in a representative example of polyurethane synthesis. For convenience, a diisocyanate and a diol are shown below. When crosslinked polyurethane is desired then diisocyanate is used with a polyol crosslinking agent, which has three or more functionalities per molecule to enable formation of fully branched/crosslinked networks. PU can be applied to a wide range of substrates. However, traditional PU coatings do not possess anti-smudge properties.
Epoxy coatings typically have two mutually reactive components that are stored separately. One component bears epoxide moieties. The other component bears hardeners that comprise hydroxyl, amino, amine, imine, anhydride, or carboxyl groups. When the two different components are mixed together, they produce a crosslinked film or coating. Epoxy coatings/adhesives can be applied to a wide range of substrates. However, traditional epoxy coatings do not possess anti-smudge properties.
There is a need for amphiphobic (e.g., anti-smudge) coatings that are optically clear and durable.